DEVELOPMENT. 
219 
and that it was a carnivorous, hot-blooded Mammal. Cer¬ 
tain structures always co-exist. Animals with two occipi¬ 
tal condyles, and non - nucleated blood - corpuscles, suckle 
Fig. 179. 
Fig. 179.—Arm and Leg of Man, as they are when he gets down on all-fours. Fig. 
ISO.—Fore and Hind Legs of Tapir. Fig. 181.—Fore Leg of Seal and Hind Leg 
of Alligator. Fig. 1S2.—Wing of the Bat. S, scapula; I, ilium, or shin-bone of 
pelvis; H, humerus; F, femur; O, olecranon, or tip of the elbow; P, patella; 
U, ulna; T, tibia; R, radius; Fi, Fibula; Po, pollex, or thumb; Ha, hallux, or 
great toe. Compare the fore and hind limbs of the same animal, and the fore 
or hind limbs of different animals. Note the directions of the homologous seg¬ 
ments. 
